Exactly as I described above - by assuming fluctuations will first be buffered by battery or other storage and only addressed if required by gas peakers and increased coal-based energy production in extended periods of lower light.
It cost $100 million to build.
Batteries energy density puts them so far past green washing that in the current day and age they are Potemkin villages.
It can respond to market demand within milliseconds, and after coming online was responsible for dropping the average wholesale price of electricity by 90%.